Quake is everything.
The history of Quake and the engine family that grew out of it. id Software's milestone engines run down the middle in chronological order. Everything branching off comes from their code, and sometimes just their ideas. A lot of the shooters you've played are on here somewhere. Peach boxes got id's help or some of its tech, but not the whole engine.
The tree as a list: the major games, grouped by family, with the engine each one runs on.
Doom named it and put it on the network. Every competitive shooter mode descends from it.
Doom's WAD files let anyone build levels; Quake shipped its own scripting language. Team Fortress and Capture the Flag were born as Quake mods.
id provided Raven a modified Wolfenstein 3D engine for ShadowCaster; Raven then licensed Doom's engine for Heretic. Selling an engine became a business, and Quake's code grew into Valve's GoldSrc.
Real 3D levels and polygon models instead of flat sprites. The template every FPS still follows.
Aiming with the mouse became the default way to play, and Thresh helped make WASD the standard.
Client-side prediction made deathmatch playable over dial-up. Modern netcode starts here.
The reason people bought a 3dfx Voodoo. Hardware acceleration went mainstream.
One of the first national gaming tournaments. Thresh won Carmack's Ferrari.
Shared demo files made speedrunning a community sport.
id started releasing its retired engines' source code (Doom in 1997, then GPL from 1999). Source ports still run Doom and Quake today.
Every surface lit and shadowed the same way, in real time, with normal maps. Modern engines light a scene the same way.
One huge streamed texture instead of repeating tiles (ET: Quake Wars, then Rage). Big engines still stream textures this way.
Binary space partitioning sorted Doom's walls fast enough for a 1993 PC. BSP levels ran shooters for a decade.
Quake worked out ahead of time what each room can see and how it is lit, so the game only drew what mattered.
Films shot inside a game engine. Recorded demos turned players into directors.
Physics quirks turned into skill: rocket jumps, strafe jumps, bunny hops.
Quake III's shader scripts described how every surface looks and moves in plain text files.
One of the first big games on Vulkan, and a showcase for the new API.
id Tech 8 treats ray-traced lighting as the starting point, not an option.
id's own games. Nearly every one debuted a new engine, and everything else on this page grows out of them.
Founded by ex-Starbreeze devs, brought into the family under ZeniMax. Every modern Wolfenstein runs on id Tech.
Valve licensed Quake and heavily modified the QuakeWorld code into GoldSrc, folding in some Quake II tech along the way. Source grew out of that, then Source 2.
Founded by ex-Call of Duty devs, who then built on Source. Both roads lead home.
The first Call of Duty ran on id Tech 3 with Ritual's ÜberTools, the same base as Medal of Honor: Allied Assault. Infinity Ward rebuilt it into the IW engine, Treyarch (T) and Sledgehammer (S, H) grew their own forks of it, and it all came back together in IW 9.0.
Raven built on id's code from 1993 to 2009: ShadowCaster's modified Wolfenstein engine, Doom's engine, then Quake's, Quake II's, Quake III's and Doom 3's. They even made a Quake.
Through the late 90s and early 2000s, half the shooters on the shelf were running id's code. Later, its sister studios forked it into engines of their own.
Quake Champions runs on a deliberate id Tech + Saber3D hybrid. Starfield got id Tech features ported in; the rest got id's help with the feel.
id gave the source away. Quake in 1999, Quake II in 2001, Quake III in 2005. People are still building on it.